Re-use a single SmallString instance to reduce the stack frame size
Re-use a single SmallString instance to reduce the stack frame size

In certain builds (msan), this can otherwise exceed the stack frame
limit set for certain environments.

git-svn-id: ffe668792ed300d6c2daa1f6eba2e0aa28d7ec6c@241894 91177308-0d34-0410-b5e6-96231b3b80d8

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